Effect of short-term natural weathering on MSWI and wood waste bottom ash leaching behaviour.

Short term natural weathering was applied on municipal solid waste (MSW) and wood waste incinerator bottom ash (BA). The materials were analysed at different steps of treatment and characterized for chemical and mineralogical composition. Both short and long term leaching behaviour of main elements and heavy metals were investigated as well. Lead, zinc and copper were the main heavy metals to be released. After 12 weeks of treatment the concentration of leached zinc decreased. Lead concentration was not found to be influenced by pH and decreased only for the biomass samples. Weathering did not have beneficial effects on copper leaching, which was well described by complexation processes with DOC. The findings from the experimental campaign indicated that weathering reactions improved the mineral stability of the analysed materials but, in contrast with previous works, the treatment was not sufficient to guarantee pH stability and to comply with leaching law limits.